Recent advances in network technology are creating a shift in network access away from narrow band access services such as dialup, and towards broadband access services such as FFTH (Fiber To The Home). Along with this shift, an increasing number of applications require real time operation (streaming, VoIP, net-banking, etc.) rather than applications (mail, World Wide Web, data transmission) that are not greatly affected by changes in communication bandwidth. The demand for a network with a stable communication bandwidth is increased because of this change.
However in current network services, multiple users share the bandwidth in a best efforts type (throughput is not guaranteed) situation. Providing a stable bandwidth is therefore difficult and network services cannot always cope with real time network applications. This situation has created a demand for network services that offer use of different bandwidths by contract.
To achieve this type of bandwidth control, traffic shaping using the leaky bucket algorithm has been proposed to guarantee the bandwidth for variable length packet communication that is currently most often used on networks.
According to technology disclosed in JP 2003-198611 A, thresholds expressing the MFR (minimum frame rate) (MFR refers to minimum guaranteed bandwidth) and the PFR (peak frame rate) (PFR refers to maximum allowable bandwidth) are set on the leaky bucket. This technology allows holding packets and sending packets from queues whose packets are lower than the minimum frame rate. This technology also allows sending packets from queues whose packets are below peak frame rate when surplus bandwidth is available. Sending frames is prohibited from queues whose packet level exceeded the peak frame rate regardless of the packets. This method can therefore control the minimum frame rate and peak frame rate.
The text, “Standard Token Bucket Terminology” by P. F. Chimento describes the token bucket operating principle. Also, Section 4.4.2 of the “Traffic Management Specification Version 4.0” by the ATM Forum Technical Committee describes the leaky bucket operating principle.